Method for operating a worm centrifuge having a pressurized gas introduction

Abstract

A method for operating and improving the throughput and efficiency of a worm centrifuge by introducing, at a controlled frequency, successive pressure surges into the concentrated sludge fraction within the bowl separator preceding the solids discharge opening whereby the pulse frequency and the level of pressure are controllable and can be controlled as a function of the sludge fraction throughput through the separator.

I claim as my invention: 
     
       1. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry comprising the steps: introducing a slurry into a rotary bowl separator rotatable about an axis and having a worm therein to separate the slurry into a liquid fraction and a sludge fraction containing solids;   introducing a pressurized gas into concentrated sludge within the bowl in successive pressure surges;   and increasing a pulse frequency of said pressure surges of the pressurized gas as a function of increasing sludge fraction solids throughput through the centrifuge.   
     
     
       2. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including maintaining a controlled output of the solids and the liquid fraction and varying the pressure of the gas introduced into said concentrated sludge.   
     
     
       3. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including varying the pulse frequency of said pressure surges of the gas introduced into the concentrated sludge;   and varying the pressure of the gas introduced into the concentrated sludge.   
     
     
       4. A method of operating a rotary bowl worm centrifuge for separating liquid solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including introducing the pressurized gas at a plurality of locations within the bowl at spaced axial locations.   
     
     
       5. A method of operating a rotary bowl worm centrifuge for separating liquids/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: wherein the slurry introduced into the separator has a solids content in the range of 0.5% to 1.5% and the sludge fraction is discharged with a solids content in the range of 5% to 10%.   
     
     
       6. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: wherein the successive pressure surges are controlled and introduced in the range of between 1 and 300 pulses per minute.   
     
     
       7. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: wherein the pressurized gas is introduce at a pressure in the range of 10 to 15 bar.   
     
     
       8. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: wherein the pressurized gas is heated prior to introduction into the centrifuge.   
     
     
       9. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: wherein the pressurized gas is in the form of steam.   
     
     
       10. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including varying pauses between successive pressure surges.   
     
     
       11. A method of operating a rotary bowl worm centrifuge for separating liquids/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including varying the time duration of individual pressure surges.   
     
     
       12. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry in accordance with the steps of claim 1: including measuring a solids content of slurry delivered to the centrifuge; and increasing the pulse frequency of the pressurized gas as a function of an increase of the solids content measurement of the delivered slurry.   
     
     
       13. A method of operating a rotary bowl worm centrifuge for separating liquid/solids mixtures such as thickening a thin slurry comprising the steps: introducing a slurry into a rotary bowl separator rotatable about an axis and having a worm therein to separate the slurry into a liquid fraction and a sludge fraction containing solids and having an outlet for said liquid fraction and an outlet for said sludge fraction;   introducing a pressurized gas into concentrated sludge within the bowl through a gas pressure line leading into the bowl in successive pressure surges;   and increasing a pulse frequency of said pressure surges of the pressurized gas as a function of increasing sludge fraction solids throughput through the centrifuge.